India's population has grown more than 180 million in the last ten years to 1.2 billion, but its proportion of girls has fallen to its lowest rate since independence, according to the latest census.

Officials said they were alarmed at the tilting of India's gender balance further towards boys amid growing concerns over the impact of female foeticide by families who prefer sons.

According to the census 914 girls are being born per 1,000 boys compared with 927 per 1000 in 2001. India now has 623.7 million males and 586.5 million females. Census Commissioner C. Chandramauli said the figures were a "matter of grave concern".

Dr A.L. Sharada, of the charity Laadli, which works to raise the status of Indian girls, said girls are still seen as a burden in India. "Marriage and dowry is the biggest burden for parents in India and the amount of money the parents need to shell out for a daughter's big fat wedding makes them a burden for their parents," he said. Boys, however, are seen as future breadwinners who will stay with their families.

The alarm over India's declining sex ratio overshadowed the striking growth in its population to within 120 million of overtaking China as the world's most populous country. India's population is forecast to overtake that of China in 2026, but the census revealed early signs that the growth is starting to slow.

While it has more people than the United States, Indonesia, Brazil, Japan, Bangladesh, and Pakistan combined, its growth rate had fallen to 17.6 per cent from 21.5 per cent ten years ago. It is the first time population growth has fallen since 1921.